Year	% of total
1995	97.6
2000	97.7
2001	97.5
2002	97.6
2003	97.8
2004	97.7
2005	97.5
2006	97.5
2007	97.4
2008	97.5
2009	99.4
2010	99.3
2011	99.6
2012	99.8
2013	99.8
2014	99.8
2015	99.9
2016	99.7
2017	99.9
2018	99.6
2019	99.6